A prior art process of setting the length of an upper steering arm is shown in German Patent No. DE 197 47 949 C2. Here, the actual length of the upper steering arm is determined by a length sensor and the position of lift of the lifting mechanism is determined by a lift sensor. For each lift position, a nominal length of the upper steering arm is stored. The actual length of the upper steering arm is compared with the nominal length. If the two values deviate, a power drive is actuated which moves the upper steering arm to its nominal length. An attached implement is thus lowered and lifted with identical movement sequences. However, when used with soil working implements, this process can lead to non-optimum treatment of the soil.
Further processes for setting the length of an upper steering arm are shown in U.S. Pat. No. 5,188,502. This patent deals with setting the length of two upper steering arms of a construction machine. With one described process, one or several positions can be set automatically from any starting position. The movement from the starting position to the stored end position is continuously calculated. Depending on the starting position, different movement sequences can take place into the end position. Furthermore, the implement can be lifted and lowered in parallel without pivoting the implement.